test datatype for ANY

Hi there,

How can I test the type of a parameter passed to a function via ANY data type?
I want something like this:

CREATE OR REPLACE FUNCTION myfunction(_param ANY) RETURNS INTEGER AS $$
    BEGIN
        IF "_param IS OF INTEGER TYPE" THEN
            -- do something with INTEGER
        END IF;
        IF "param is of BOOLEAN TYPE" THEN
            -- do something with BOOLEAN
        END IF;
        RETURN;
    END;
$$ LANGUAGE plpgsql;


Thanks,
Nosy